Keyser was the wealthy daughter of a Stock Exchange member, and of all of Edward VII"s mistresses, with the exception of socialite Jennie Jerome, she was the best accepted within royal circles, including by Edward VII"s wife, Alexandra of Denmark.
She remained with Edward VII until his death in 1910. Keyser was born Elizabeth Agnes Keyser in July 1852 at Great Stanmore in Middlesex, the daughter of Charles and Margaret Keyser. Her father was a partner in a stock exchange firm Ricardo and Keyser.
She died at Buckland House, Farringdon, Berkshire on 11 May 1941, aged 89.
During the First World War the hospital used 9 Grosvenor Gardens to nurse British officers, including the novelist Stuart Cloete. The hospital became and later King Edward VII"s Hospital Sister Agnes.
